Book Jackets: More Than a Marketing Tool
That dust jacket that comes with every new hard cover book: Do you really need it?
The quick answer is, yes, the jacket protects the book cover from wear, tear, and spills.
The longer answer is, yes, the jacket protects the book cover from wear, tear, spills, and over time, fading and weathering.
Believe it or not, a jacket can be more valuable than the book it protects, if the jacket is well taken care of. Thus, removing it while you read the book won't protect the book as well but may help retain the value of the cover, if you're a collector.
To protect both the book and the jacket, consider investing in a plastic sheet that will encase the outside of the jacket. Jackets easily tear or take on spills, smears, and marks the book would have taken on, and you can protect the jacket from those with a plastic covering.
If you decide to remove the jacket while reading the book, store it carefully. Jackets tend to curl and lose their bookly shape. If they end up under other things, you will end up with unintended creases. Instead, fold the jacket along a natural crease or, if you have a long enough drawer, straighten out full length until you need to wrap the jacket around the book again.